Living in blissful ignorance, I thought all early model W126 ATE calipers were the same. It very well could have been off a gasser car. I'm pretty sure I took it off a first gen W126, though. I don't remember exactly what model the car was since I thought they were going to be the same calipers.

Since I am free most of tomorrow, I'll pop off the LF caliper on my car and see if the dust boot will fit via physical comparison. The question is: do I have the right rebuild kit for my car but the wrong test caliper, or is the rebuild kit wrong all together? That's what I aim to find out.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge